diff --git a/lld/MachO/InputFiles.cpp b/lld/MachO/InputFiles.cpp
--- a/lld/MachO/InputFiles.cpp
+++ b/lld/MachO/InputFiles.cpp
@@ -139,12 +139,28 @@
   return None;
 }
 
+static bool checkSimulatedPlatform(PlatformKind lhs, PlatformKind rhs) {
+  // Mapping of platform to simulator and vice-versa.
+  static const std::map<PlatformKind, PlatformKind> platformMap = {
+      {PlatformKind::iOS, PlatformKind::iOSSimulator},
+      {PlatformKind::iOSSimulator, PlatformKind::iOS},
+      {PlatformKind::tvOS, PlatformKind::tvOSSimulator},
+      {PlatformKind::tvOSSimulator, PlatformKind::tvOS},
+      {PlatformKind::watchOS, PlatformKind::watchOSSimulator},
+      {PlatformKind::watchOSSimulator, PlatformKind::watchOS}};
+
+  auto iter = platformMap.find(lhs);
+  return iter != platformMap.end() && iter->second == rhs;
+}
+
 static bool checkCompatibility(const InputFile *input) {
   Optional<PlatformInfo> platformInfo = getPlatformInfo(input);
   if (!platformInfo)
     return true;
-  // TODO: Correctly detect simulator platforms or relax this check.
-  if (config->platform() != platformInfo->target.Platform) {
+
+  if (config->platform() != platformInfo->target.Platform &&
+      !checkSimulatedPlatform(config->platform(),
+                              platformInfo->target.Platform)) {
     error(toString(input) + " has platform " +
           getPlatformName(platformInfo->target.Platform) +
           Twine(", which is different from target platform ") +
diff --git a/lld/test/MachO/invalid/incompatible-arch.s b/lld/test/MachO/invalid/incompatible-arch.s
--- a/lld/test/MachO/invalid/incompatible-arch.s
+++ b/lld/test/MachO/invalid/incompatible-arch.s
@@ -30,6 +30,21 @@
 # RUN:  -o /dev/null 2>&1 | FileCheck %s --check-prefix=OBJ-VERSION
 # OBJ-VERSION: {{.*}}test_x86.o has version 10.15.0, which is newer than target minimum of 10.14.0
 
+## Test that simulators platforms are compat with their simulatees.		
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-ios10.15.0 %s -o %t/test_x86_ios.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-apple-ios10.15.0-simulator %s -o %t/test_x86_ios_sim.o
+
+# RUN: %lld -dylib -platform_version ios-simulator 10.15.0 10.15.0 %t/test_x86_ios.o -o /dev/null
+# RUN: %lld -dylib -platform_version ios 10.15.0 10.15.0 %t/test_x86_ios_sim.o -o /dev/null
+
+# RUN: not %lld -dylib  -platform_version watchos-simulator 10.15.0 10.15.0 %t/test_x86_ios.o \
+# RUN:	-o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-SIM
+# CROSS-SIM: {{.*}}test_x86_ios.o has platform iOS, which is different from target platform watchOS Simulator
+# RUN: not %lld -dylib  -platform_version watchos-simulator 10.15.0 10.15.0 %t/test_x86_ios_sim.o \
+# RUN:	-o /dev/null 2>&1 | FileCheck %s --check-prefix=CROSS-SIM2
+# CROSS-SIM2: {{.*}}test_x86_ios_sim.o has platform iOS, which is different from target platform watchOS Simulator
+	
+
 .globl _main
 _main:
   ret